public virtual UsersGroup CreateChildUserGroupOf(string parentGroupName, string usersGroupName)
     {
       UsersGroup parent = GetUsersGroupByName(parentGroupName);
       Guard.Against<ArgumentException>(parent == null,
                                        "Parent users group '" + parentGroupName + "' does not exists");

       UsersGroup group = CreateUsersGroup(usersGroupName);
       group.Parent = parent;
       group.AllParents.AddAll(parent.AllParents);
       group.AllParents.Add(parent);
       parent.DirectChildren.Add(group);
-      parent.AllChildren.Add(group);
+            foreach(UsersGroup prnt in group.AllParents)
+            {
+                prnt.AllChildren.Add(group);
+            }
+
         return group; 
     }